1. Field of the Invention
The invention relates to a dosing device for liquids with a distributor rail, and a plurality of dosing units for a liquid that are hydraulically connected to the distributor rail, each dosing unit having a valve unit on which a piston-cylinder unit for drawing in and measured discharging of the liquid is detachably arranged, each valve unit having a hydraulic connection element for detachable hydraulic connection to the distributor rail.
2. Description of Relation Art
Overall, the invention relates to a dosing device for liquids as used in semi-automated or fully automated production dosing installations for filling samples or the like, particularly in the biological, chemical or pharmaceutical industry. A plurality of sample containers arranged next to one another are simultaneously filled with the desired liquid by using a multi-channel system made of a plurality of dosing units arranged next to one another.
Once a dosing cycle or a period of dosing has been completed, and when the liquid to be dosed is changed, all parts of the dosing installation exposed to the liquid have to be cleaned, possibly autoclaved or sterilized. In the case of some liquids, this is downright difficult and so there has already been a proposal for a dosing installation that is improved in terms of application and cleaning (Brochure of the Assignee of the assignee of this application, BRAND GMBH+CO KG, “Dosieranlagen und-systeme” [Dosing installations and dosing systems], 9944-93, 10/0903; WO-A-00/49418 corresponds to U.S. Pat. No. 6,593,146 B1). A dosing device for the liquid to be dosed is part of such a dosing installation. This dosing device is constantly connected to a liquid storage container or a storage line. The dosing device is equipped with electrical devices, drives and various lines required for operation.
The known dosing device, on which the invention is based, has a distributor rail and a plurality of dosing units for the liquid to be dosed that are hydraulically connected to the distributor rail. It is typical for five dosing units to be arranged on a distributor rail. Each dosing unit has a valve unit and a piston-cylinder unit detachably arranged on the valve unit. The valve unit typically has a suction valve, a discharge valve and a laterally protruding discharge cannula that can be removed from the valve unit. Each valve unit has a hydraulic connection element for detachable hydraulic connection to the distributor rail. The distributor rail itself has an elongate fluid supply line, which has at its end a supply connection for the liquid and has dosing unit connections distributed laterally along its length, arranged with equidistant spacing, which dosing unit connections are detachably coupled to the hydraulic connection elements of the dosing units.
The description of the dosing device provided above and the description of the dosing device provided below assume that, overall, the dosing device is assembled. Parts, which in principle are detachably interconnected, are interconnected. This illustrates the relationships.
Assigned to the dosing device is a motor-driven drive device, which is detachably coupled to connecting heads on the piston rods of the piston-cylinder units via a coupling device. Movement of the coupling device can lift and lower all piston rods of the adjacent piston-cylinder units in a synchronous fashion for sucking in and dosed discharge of the liquid.
In the known dosing device constituting the starting point for the teaching of the invention, the distributor rail is produced as a block of sterilizable and autoclavable metal, made in particular of aluminum or stainless steel. The fluid supply line and the dosing unit connections are formed in the block. On this distributor rail, there are also laterally spaced apart strips of hooks, which form mechanical connection elements detachably engaged with corresponding mechanical connection elements on the dosing units. Thus, on the one hand, the block-like distributor rail forms the fluid supply for the dosing units and, on the other hand, the mechanical support for the dosing units.
Measures have already been taken in the known dosing device in order to optimize it in respect of cleaning. Specifically, there, provision is made for the piston cylinder units to be designed as replaceable parts made of preferably recyclable and preferably injection-moldable plastic and to be used interchangeably. Furthermore, provision is also made for the valve units to be designed, at least to the greatest extent, as replaceable parts made of preferably recyclable and preferably injection-moldable plastic. The result of this is that it is only the complex and high-quality distributor rail that has to be cleaned and, preferably, sterilized and/or autoclaved. All add-on parts can quickly be replaced.